Configurations and methods for power generation with integrated LNG regasification

Abstract

LNG cold is used in a plurality of cycles in a combined power plant to increase power output. Especially preferred plant configurations integrate a combined cycle power plant with a regasification operation in which in a first stage LNG cold provides cooling in an open or closed power cycle. Most preferably, a significant portion of the LNG is vaporized in the first stage. In a second stage LNG cold provides cooling for a heat transfer medium that is used to provide refrigeration for the cooling water to a steam power turbine and for an air intake chiller of a combustion turbine in the power plant.

1. A power plant, comprising:
 a first heat exchanger that is configured to receive LNG and to provide refrigeration to a working fluid to thereby generate heated LNG, and an expander configured to receive the working fluid to thereby drive a generator and to produce an expander discharge; 
 wherein the first heat exchanger is further configured to allow heat exchange between the expander discharge and the LNG; 
 a second heat exchanger that is configured to receive the heated LNG and to provide refrigeration to a heat transfer medium fluid to thereby generate vaporized LNG; and 
 a third and a fourth heat exchanger, configured to receive the heat transfer medium and to provide refrigeration for an intake air cooler and a steam turbine cycle, respectively. 
 
   
   
     2. The power plant of  claim 1  wherein the working fluid is circulated in a closed cycle. 
   
   
     3. The power plant of  claim 2  wherein the working fluid is a multi-component working fluid. 
   
   
     4. The power plant of  claim 1  wherein the first heat exchanger is configured such that the heated LNG is at least partially vaporized. 
   
   
     5. The power plant of  claim 1  wherein the heat transfer medium comprises a glycol-water mixture. 
   
   
     6. The power plant of  claim 1  wherein the LNG in the first heat exchanger has a temperature of between −250° F. to −50° F., and wherein the LNG in the second heat exchanger has a temperature of between −50° F. to 40° F. 
   
   
     7. The power plant of  claim 1  wherein first and second heat exchangers are configured such that LNG is vaporized at a flow rate of between about 200 million standard cubic foot per day and 2 billion standard cubic foot per day. 
   
   
     8. The power plant of  claim 1  further comprising a pump that pumps the LNG to pipeline pressure before the LNG enters the first heat exchanger. 
   
   
     9. The power plant of  claim 1  further comprising a water condensate line that feeds water condensate from the intake air cooler to a fuel gas humidifier. 
   
   
     10. The power plant of  claim 1  wherein the working fluid is the LNG to thereby form an open power production cycle. 
   
   
     11. The power plant of  claim 10  further comprising a pump that pumps the LNG to supercritical pressure. 
   
   
     12. The power plant of  claim 11  wherein the first heat exchanger comprises a component selected from the group consisting of a fuel-fired heater, a sea water heater, a flue gas heater, and a cryogenic process component. 
   
   
     13. The power plant of  claim 11  wherein the expander is configured to expand the supercritical LNG to pipeline pressure. 
   
   
     14. The power plant of  claim 11  further comprising an auxiliary heat exchanger that is configured to preheat the supercritical LNG using expander discharge from the expander. 
   
   
     15. The power plant of  claim 14  wherein the first heat exchanger and the auxiliary heat exchanger are configured such that the supercritical LNG has a temperature of about 300° F. to 500° F. 
   
   
     16. A method of operating a plant, comprising:
 heat exchanging LNG in a first heat exchanger against an expander discharge stream to provide refrigeration to a working fluid and to thereby generate heated LNG; 
 using the working fluid to drive an expander that is coupled to a generator to thereby generate electricity and the expander discharge stream; 
 further heating the heated LNG in a second heat exchanger to provide refrigeration to a heat transfer medium fluid and to thereby generate vaporized LNG; and 
 using the heat transfer medium in third and fourth heat exchangers to provide refrigeration for an intake air cooler and a steam turbine cycle, respectively. 
 
   
   
     17. The method of  claim 16  wherein the first heat exchanger is configured such that the heated LNG is at least partially vaporized. 
   
   
     18. The method of  claim 16  wherein the working fluid is a multi-component working fluid. 
   
   
     19. The method of  claim 16  wherein the working fluid is the LNG. 
   
   
     20. The method of  claim 16  wherein the LNG is pumped to at least pipeline pressure before entering the first heat exchanger.